This invention relates to apparatus for separating particles from a flow of dirty liquid such as machine tool coolant. More particularly, the invention relates to apparatus in which final cleaning of the liquid is effected by a cyclonic separator which produces a clean flow of liquid and also discharges a downward stream of dirty liquid -- commonly called underflow -- which contains particles removed from the liquid delivered to the cyclonic separator.
Apparatus of this general type is disclosed in Marriott U.S. Pat. No. 3,456,797 and in Estabrook U.S. Pat. No. 3,540,588 and, in each instance, the incoming dirty liquid is precleaned prior to being delivered to the cyclonic separator in order to reduce damage to the pump which serves the separator. Also, the dirty underflow discharged from the cyclonic separator is cleaned before being recirculated, the cleaning of the underflow being referred to as aftercleaning and serving to reduce the recirculation of fines.